The present invention relates generally to setting tools for packers and more particularly to a hydraulic setting tool for packers, which is capable of setting the packer and opening the packer valve in one trip.
Generally, the production efficiency of an operating oil and/or gas well decreases over time. This is due to a number of factors. In some cases, it is simply due to the fact that a reservoir containing hydrocarbons is near depletion. In many other cases, it is due to the fact that a path along which the hydrocarbons flow becomes blocked. This can occur for a number of reasons, such as production screens becoming plugged and the closing of a fracture through which the hydrocarbons flow. When this occurs, the well needs to undergo what is known in the art as a “workover.” A workover is an operation to open the path along which hydrocarbons flow.
During a workover, production tubing is removed from the well and workover tools are sent downhole in its place. One of the workover tools is a packer. A packer is a device placed in the region of the well that needs treatment. The packer isolates the region needing treatment from the rest of the well. Furthermore, the packer has a valve that can be opened and closed to control the flow of treatment fluid into the subterranean formation. When the workover is complete, the packer is drilled out of the well and the production tubing is inserted back into the well thereby enabling production to resume.
In order to install packers into the well and control the opening and closing of their valves, specialized equipment known as “setting tools” have been developed. Generally, there are two basic types of setting tools, those characterized as mechanical and those characterized as hydraulic. Both types of setting tools are attached at the end of a workstring and are operable from the surface.
Conventional mechanically operated setting tools require that the workstring be rotated in order to set the packer. This raises a number of problems in horizontal wells. For one, rotation of the workstring in a horizontal well can cause the workstring to break. Furthermore, rotation of the workstring at the surface may cause a delayed rotation downhole or no rotation at all. In either case, the well operator cannot be certain that the packer has been set. Drag spring mechanical setting tools have recently had the additional problem of not setting the packer when used in synthetic fluids. These drag spring mechanical setting tools do not offer enough resistance to rotate properly in the new synthetic fluids and thereby fail to set the packers.
Conventional hydraulic setting tools typically employ the use of a ball or plug to create the necessary fluid pressure to activate the packer. A drawback of this technique is that the ball or plug has to be removed from the workstring after the packer is set before performing additional operations. This requires recirculation of the fluid to the surface, which in turn takes time and adds expense to the operation.
A further drawback of conventional mechanical and hydraulic setting tools is that it typically requires at least two trips downhole with the workstring to accomplish the tasks of setting the packer, opening the packer valve and pumping the treatment fluid into the subterranean formation through the packer. The necessity of two trips to accomplish these tasks takes time and thus adds expense to the operation.
Furthermore, conventional setting tools are limited in that multiple setting tools are typically required to set different size packers. This is particularly problematic in offshore applications where space is limited and transporting and storing multiple setting tools on site can be a challenge.